Falls affect millions of people each year and result in significant injuries, particularly among the elderly. In fact, it has been estimated that falls are one of the top three causes of death in elderly people. A fall is defined as a sudden, uncontrolled and unintentional downward displacement of the body to the ground or a lower level, followed by contact (such as an impact) with the ground or lower level, after which the body stays down on the ground.
Personal Help Buttons (PHBs) are available that require the user to push the button to summon help in an emergency. When pressed, the PHB initiates a call to a call centre and then allows the user to communicate with call centre staff who will arrange for help to be sent to the user as required. However, if the user suffers a severe fall (for example if they are knocked unconscious), the user might be unable to push the button, which might mean that help doesn't arrive for a significant period of time, particularly if the user lives alone or if no-one witnesses the user fall.
PHBs have therefore been improved to include one or more movement sensors whose measurements are processed in order to detect a fall by the user and to trigger a call without the user having to press the button on the PHB. Most existing fall detectors make use of an accelerometer (usually an accelerometer that measures acceleration in three dimensions) and they try to infer the occurrence of a fall by processing the time series generated by the accelerometer. Some fall detectors can also include an air pressure sensor, for example as described in WO 2004/114245. The detection algorithms are typically designed for low power consumption, such that there is no need for frequent battery replacement or recharging. In addition, in some fall detectors, an alert is only triggered or initiated if the user does not stand up within a predetermined time period following a detected fall (sometimes referred to as the “revocation period”).
The use of a revocation period introduces a delay between a fall event occurring, and contact being made with the call centre. Typically, the revocation period is about 20 to 30 seconds, although it can be set to a different value. Furthermore, depending on the actual number of incoming calls at the call centre when the emergency call is triggered, the call may be placed in a queue, further delaying the dispatch of help to the user. For someone who has fallen and urgently requires help, any delay can significantly affect their chances of survival.
The delay can also be serious if the fall has been caused by some underlying health-related issue. For example, if there has been a failure in the user's vital system, such as a stroke or a cardiac arrest, then any delay in receiving emergency help can have significant consequences for the user.
Therefore, there is a need for an improved fall detector or fall detection system and a method of operating the same that overcomes the problems with the use of a revocation period. More generally, there is a need for an improved fall detector or fall detection system and method of operating the same in which the time taken to get help to a user who has suffered a fall can be reduced if that user is urgently in need of help.